Torsion bar chair control

ABSTRACT

Upstanding arms of a U-shaped spindle-mount, support a tube extending horizontally to one side of the mount. A main frame, also U-shaped, has a pair of spiders rockable on the tube and associated with another tube through a tensioning arm and adjustment screw. The tubes are end-to-end, separated by a bushing, and receive a torsion bar therethrough, the outer end of each tube being crimped onto the opposite square ends of the torsion bar.

United States Patent [72] inventor Peter A. Fuhrman 2,991,125 7/1961 Lie 297/304 Waterloo, Ontario, Canada 3,131,904 5/1964 Lie 248/373 [211 App]. No. 802,021 3,185,429 5/1965 Meinhardt 248/373 [22] Filed Feb. 25, 1969 3.240.528 3/1966 Ciuffini et a1. 297/303 (45] Patented July 13,1971 3,250,567 5/1966 Parrott 297/304 [73] Assignee Bliss & Laughlin Industries, Incorporated 3,464,663 9/1969 Blomborg 297/303 Oak Brook, 11!. 3,480,249 11/1969 Lie 248/373 FOREIGN PATENTS Australia 7 hill 5 Drawing Figs. Primary Examiner-Marion Parsons, J r. 521 US. Cl 248/373, Naughm 297/304 [51] Int. Cl A47: 3/023 [50] Field of Search 248/373. T C upstanding arms f a U shaped pindle mount 374,389; 297533.302, 303. 304; 16/75 support a tube extending horizontally to one side of the mount. A main frame, also U-shaped, has a pair of spiders [56] References Cited rockable on the tube and associated with another tube UNITED STATES PATENTS through a tensioning arm and adjustment screw. The tubes are 2,718,257 9/1955 Lie 248/373 end-to-end, separated by a bushing, and receive a torsion bar 2,935,119 5/1960 Lie 297/303 therethrough, the outer end of each tube being crimped onto 2,971,569 2/1961 Parrott et a1 248/373 the opposite square ends of the torsion bar.

SI [52 q 68 L l l -1 7| I 4 TORSION BAR CIIAIR CONTROL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to chair controls, and more particularly to chair controls of the torsion bar-type, and of compact construction, facilitating installation in a variety of chairs.

2. Description ofthe Prior Art Torsion bar controls for chair seats and backs are well known. Examples are described in the following patents:

2,424,753 July 29, 1947 Herold 2,718,257 Sept. 20, 1955 Lie 2,760,553 Aug. 28, 1956 Lie 2,778,409 Jan. 22, 1957 Soderberg 2,784,767 Mar. 12, 1957 Soderberg 2,845,991 Aug. 5, 1958 Soderberg 2,935,119 May 3,1960 Lie 2,971,569 Feb. 14, 1961 Parrott et al. 2,991,125July 4,1961 Lie 3,027,191 Mar. 27, 1962 Lie 3,162,420 Dec. 22, I964 Lie 3,185,429 May 25, 1965 Meinhardt 3,240,528 Mar. 15, 1966 Ciuffini et al. 3,250,567 May 10, 1966 Parrott In spite of this substantial amount of prior art, there has remained a need for a low-cost chair control of compact construction and neat appearance, and which is reliable and durable in operation, and which will not cause uneven loading or wracking of the chair itself. The present invention is an answer to this need.

SUMMARY OF THE INVENTION Described briefly, in a typical embodiment of the present invention, first and second tubes are disposed in substantially an end-to-end relationship, with a bushing between the facing ends, and have colinear axes. A torsion bar is received on the axes of the tubes, and extends throughout their lengths. The ends of the torsion bar are squared, and each of the tubes has its outer end crimped onto the torsion bar end for nonrotating relationship therebetween.

One of the tubes is mounted on a post mount and receives a pair of spiders in fixed spaced relationship to each other, the spider pair being rockably mounted on the tube. The spider pair serves as a seat mount, and a torque arm extending radially from the other of the two tubes has an adjustment screw and crank arm at its distal end, the screw engaging one of the spiders. There is provided in this way a compact, low-cost,v

durable and reliable chair control, easily mounted to a variety of seats and capable of serving its intended purpose without wracking of the seat.

BRIEF DESCRIPTION OF THE DRAWINGS The full nature of the invention will be understood from the accompanying drawings and the following description and claims.

FIG. 1 is a front elevational view on a small scale, showing a chair incorporating a control according to a typical embodiment ofthe invention.

FIG. 2 is an enlarged front elevational view of the chair control itself.

FIG. 3 is a top plan view thereof, with portions broken away to show interior details.

FIG. 4 is a section taken at line 4-4 in FIG. 3 and viewed in the direction of the arrows.

FIG. 5 is a right-hand elevational view of the chair control, illustrating the adjustment means from another aspect.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, and particularly FIG. 1, the chair 11 is provided with a base 12 having a spindle or post 13 thereon. The chair control 14 of the present invention is mounted on the post anda seat 16 is mounted on the chair control. The chair may have arms 17 and a back 18 or it might have other configurations. In any event the illustrated embodiment of the invention is best adapted to mounting centrally under the seat, regardless of whether the chair has one or another of a variety of possible configurations.

Referring now more particularly to the other views of the drawings, a spindle bushing 19 atopthe spindle 13 receives the horizontal portion 21 of a U-shaped inner frame 22 having upstanding arms or walls 23 and 24. The inner frame may be affixed to the spindle bushing with a washer 26 atop the portion 21, the latter being retained by an upset portion 27 at the upper end of the bushing. It is possible that the inner frame can be mounted otherwise to the spindle or spindle bushing for a fixed connection or connection rotatable on the spindle axis.

The inner frame portion 21, bridging the space between the lower margins of the arms 23 and 24 thereof, serves to maintain alignment of apertures 28 and 29 provided in these arms. These apertures receive a tube 31 of circular crosssection, having its longitudinal axis 32 perpendicular to the walls 23 and 24 and centered in the apertures 28 and 29. The tube ex-' tends to the right-hand side of the frame a substantial distance, approximately equal to the overall width of the frame, and terminates at end 33.

Tube 31 has a pair of longitudinally extending slots 34 ancl 36 therein receiving lugs 37 and 38, respectively of a pawl 39" which extends radially from the tube with respect to the axis 32, and engages the upper end of the spindle at 41. This" prevents rotation of the tube 31 in the direction of arrow 42 in FIG. 4.

An outer or main frame 43 is provided and includes a central bridging portion 44 supporting upstanding walls 46 and and front and rear walls 48 and 49, respectively. The walls 46 and 47 are extended and have outwardly turned flanges 51 and 52, respectively, on the upper margins thereof, and serve" as a pair of spiders directly securable to the underside of theseat 16 by appropriate fasteners through the four apertures 53. This whole main frame, complete with spiders, is formed of a single plate of steel, for example, according to one aspect of the illustrated embodiment of the present invention, and the spiders are thereby securely and rigidly disposed as shown. Because of this arrangement, as will be seen, the loads from the chair are transmitted to the chair base 12 without any wracking of the seat.

Bushings 54 and 56 are received on the outer tube 31 and received in aligned apertures in the walls 46 and 47, respectively, of the main frame. The radially extending circular flanges 57 on these bushings located against the walls 28 and 29 of the inner frame serve to provide axial spacing between the inner and outer frame walls. Therefore the outer frame is" capable of rocking on the axis 32 with respect to the inn'er' frame. The limits of this rocking action are determined by engagement of the stop surface 58 (FIG. 4) of the inner frame by the lower faces 59 of the rubber bumpers 61 received in the forwardly turned flange 62 of the rear wall 49.0f the outer frame. This limits rocking of the outer frame in the direction" of arrow 42 with respect to the inner frame. A rocking in the other direction is limited by engagement of the lower edge 63- of the rear margin of the bridging portion 21 with the upper surface 64 of the bridge portion of the outer frame.

Another tube 66 of circular cross section is disposed in an end-to-end relationship to the tube 31, with a" bushing 67 disposed between the ends of the respective tubes to maintain an appropriate end spacing and permit relative rotation between the tubes with respect to the axis 32. A tension adjustment or torque arm 68 is affixed to the tube 66 at its inner end. This extends rearwardly on .a radius from axis 32 and is terminated by the rolled thread socket-69 threadedly receiving the adjustment screw 71 having the handle portion 72 and knob 73 thereon. The upper end 74 (FIG. 5) of this screw engages the underside of the flange 51 and the distance of the screw axis from the spindle axis 76 is sufiicient to permit full circle rotation of the screw by turning the handle 72.

A torsion bar 77 is received through the center of both tubes, coaxial therewith and projecting slightly beyond the ends of the tubes. This bar can be of various types of construction, but typically it is a laminated bar of square cross section throughout its length and, according to one feature of this invention, the outer distal ends 78 and 79 of the tubes 31 and 66, respectively, are crimped onto this bar to provide nonrotatable connections between the tubes and the respective ends of the bar to which they are crimped. It is possible for the ends of the tubes to be provided with the formed noncircular cross section desired to accommodate the noncircular form of whatever torsion bar ends would be used, the formed tube ends, rather than inserts, bushings, or other connections, being the important feature in this instance. Accordingly the material of the tubes can be homogeneous throughout, thus minimizing the number of parts required for appropriate connections. The bushing 67 can have a circular central aperture receivable over the corners of the torsion bar, but is preferably provided with a square central aperture slidingly receivable on the torsion bar.

In the use of the device, a certain minimum amount of torsional stress can be established in the bar during manufacture, tending to cause rocking of the outer frame on the inner frame in the direction of arrow 81 (FIG. 4) and limited by the stop 63-64 described above. Additional torsional stress can be established by rotating the adjusting screw in the direction of the arrow 82 (FlG. 3) which will move the tension adjustment arm in the direction of arrow 84 (FIG. 5) about the axis 32, thus increasing the spring load in the bar.

Because of the fact that all components of the present invention are located inboard of the torsion bar ends 86 and 87, the unit can occupy a minimum width consistent with use of a torsion bar of sufficient length to provide the desired substantially uniform torsional resistance desired as the seat is rocked or tilted backward by the occupant of the chair.

It is believed apparent from the foregoing description, that the present invention answers the needs heretofore existing in the chair control art.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being made to the appended claims.

l claim:

1. A chair control comprising:

a seat mount having a pair of horizontally spaced surfaces receivable on a chair seat, said surfaces being disposed at upper margins of horizontally spaced walls, with the lower marginal portions of said walls being bridged by a bridging portion;

a torsion bar;

first load transmitting means between one end of said torsion bar and said mount;

a post;

second load transmitting means between the other end of said torsion bar and said post;

said seat mount being sufficiently rigid to transfer seat tilting loads equally from said surfaces to said first load transmitting means;

said first load transmitting means including a first tube beginning near one of said walls and extending away from said walls in a first direction:

a first torque arm extending radially from said first tube to a point under one of said surfaces;

adjustment means associated with said ann and having a hand grip thereon to facilitate adjustment, a portion of said adjustment means bearing on said mount above said point;

said second load transmitting means including a second tube beginning at said one wall and extending through the other of said walls;

said walls being pivotally mounted on said second tube for rocking thereon.

2. The chair control of claim 1 wherein:

said first tube has an end formed to nonrotatably receive one end of said torsion bar, and said second tube has an end formed to nonrotatably receive the other end of said torsion bar.

3. The control of claim 1 wherein:

first and second bushings are received in apertures in said seat mount walls and are received on said second tube to provide bearings for rocking of said seat mount on said tube,

said bushings having radially extending flanges thereon providing axial bearings between said seat mount walls and said post mount walls;

said control further comprising a third bushing received in an end of said second tube adjacent said one wall and received in an end of said first tube adjacent said one wall, facilitating relative rotation between said first and second tubes on their longitudinal axis as said adjustment means are adjusted and as said seat mount is rocked on said second tube, the turning and rocking being resisted by torsional resilience of said torsion bar.

4. The chair control of claim 1 and further comprising:

a post mount having a pair of horizontally spaced walls with a bridge portion bridging the space between said walls,

said second tube extending through said walls and supported thereby,

means preventing rotation of said second tube in said post mount walls,

and means limiting the available degree of rocking of said seat mount on said post mount.

5. The chair control of claim 4 wherein:

said means preventing rotation of said second tube in said post mount include a longitudinally extending slot in said second tube, and a pawl received in said slot and extending radially into engagement with said bridge portion of said post mount.

6. A chair control comprising:

a seat mount connectable to a chair seat and having a pair of horizontally spaced walls fixed with respect to each other by bridge means independent of a chair seat;

a post mount;

a torsion bar;

first load transmitting means between one end of said torsion bar and said seat mount;

second load transmitting means between the other end of said torsion bar and said post mount;

said first load transmitting means include a first tube and said second load transmitting means include a second tube aligned endwise with said first tube;

said post mount including horizontally spaced parallel upstanding arms;

said second tube extending through aligned apertures in said arms and projects to one side of said post mount;

first and second bushings horizontally spaced and located on said first tube by said arms of said post mount;

said seat mount having first and second spiders received respectively on said first and second bushings, said spiders being rigidly connected together by said bridge means extending therebetween; and

said first tube having an axis colinear with the axis of said second tube, said first tube being in load transmitting relationship to one of said spiders and projecting therefrom opposite said second tube.

7. The chair control of claim 6 wherein:

said torsion bar extends through said tubes and has opposite end portions of noncircular cross section, the distal end of said first tube being crimped to fittingly receive one of said bar end portions, and the distal end of said second 

1. A chair control comprising: a seat mount having a pair of horizontally spaceD surfaces receivable on a chair seat, said surfaces being disposed at upper margins of horizontally spaced walls, with the lower marginal portions of said walls being bridged by a bridging portion; a torsion bar; first load transmitting means between one end of said torsion bar and said mount; a post; second load transmitting means between the other end of said torsion bar and said post; said seat mount being sufficiently rigid to transfer seat tilting loads equally from said surfaces to said first load transmitting means; said first load transmitting means including a first tube beginning near one of said walls and extending away from said walls in a first direction: a first torque arm extending radially from said first tube to a point under one of said surfaces; adjustment means associated with said arm and having a hand grip thereon to facilitate adjustment, a portion of said adjustment means bearing on said mount above said point; said second load transmitting means including a second tube beginning at said one wall and extending through the other of said walls; said walls being pivotally mounted on said second tube for rocking thereon.
 2. The chair control of claim 1 wherein: said first tube has an end formed to nonrotatably receive one end of said torsion bar, and said second tube has an end formed to nonrotatably receive the other end of said torsion bar.
 3. The control of claim 1 wherein: first and second bushings are received in apertures in said seat mount walls and are received on said second tube to provide bearings for rocking of said seat mount on said tube, said bushings having radially extending flanges thereon providing axial bearings between said seat mount walls and said post mount walls; said control further comprising a third bushing received in an end of said second tube adjacent said one wall and received in an end of said first tube adjacent said one wall, facilitating relative rotation between said first and second tubes on their longitudinal axis as said adjustment means are adjusted and as said seat mount is rocked on said second tube, the turning and rocking being resisted by torsional resilience of said torsion bar.
 4. The chair control of claim 1 and further comprising: a post mount having a pair of horizontally spaced walls with a bridge portion bridging the space between said walls, said second tube extending through said walls and supported thereby, means preventing rotation of said second tube in said post mount walls, and means limiting the available degree of rocking of said seat mount on said post mount.
 5. The chair control of claim 4 wherein: said means preventing rotation of said second tube in said post mount include a longitudinally extending slot in said second tube, and a pawl received in said slot and extending radially into engagement with said bridge portion of said post mount.
 6. A chair control comprising: a seat mount connectable to a chair seat and having a pair of horizontally spaced walls fixed with respect to each other by bridge means independent of a chair seat; a post mount; a torsion bar; first load transmitting means between one end of said torsion bar and said seat mount; second load transmitting means between the other end of said torsion bar and said post mount; said first load transmitting means include a first tube and said second load transmitting means include a second tube aligned endwise with said first tube; said post mount including horizontally spaced parallel upstanding arms; said second tube extending through aligned apertures in said arms and projects to one side of said post mount; first and second bushings horizontally spaced and located on said first tube by said arms of said post mount; said seat mount having first and second spiders received respectively on said first and second bushings, said spiders being rigidly connected together by saId bridge means extending therebetween; and said first tube having an axis colinear with the axis of said second tube, said first tube being in load transmitting relationship to one of said spiders and projecting therefrom opposite said second tube.
 7. The chair control of claim 6 wherein: said torsion bar extends through said tubes and has opposite end portions of noncircular cross section, the distal end of said first tube being crimped to fittingly receive one of said bar end portions, and the distal end of said second tube being crimped to fittingly receive the other end portion of said bar. 